Abstract 1971: RCC2 promotes glioblastoma through regulation of G2-M progression

Abstract

Abstract Regulator of chromatin condensation 2 (RCC2), also known as telophase disk protein of 60 kDa (TD-60), has been previously identified as a component of the chromosome passenger complex. Accumulating evidence suggested that RCC2 plays a vital role in the mitotic process and abnormal RCC2 expression is essential for cancer development including Glioblastoma Multiforme (GBM). GBM is the most lethal and frequent brain tumor. Even with the optimal therapy, the 5-year survival rate of GBM remains poor. TCGA data revealed an upregulation of RCC2 in human GBM. Our preliminary data showed that RCC2 was upregulated in PTEN knockout mice primary astrocytes, and loss of function of PTEN has been found in nearly 95% GBM patients. This indicated that RCC2 might act as a PTEN downstream regulator and promote glioblastoma progression. RCC2 has been reported to be essential for tumorigenesis which may act as a GEF for Rac1 or RalA GTPase. Coincidently, our study showed that silencing RCC2 could suppress GBM cell proliferation. Using RNA-seq, we identified 737 DEGs between control siRNA- and RCC2 siRNA-treated A1172 cells. GSEA analysis delineated G2-M progression as the most notably altered pathway by silencing RCC2. Indeed, we observed a G2-M arrest in cells with RCC2 silenced, suggesting that RCC2 is essential for G2-M progression. Additionally, the connectivity map (C-map) analysis was conducted and identified LY294002 and cephaeline as promising inhibitors for RCC2-associated gene signatures. Both LY294002 and cephaeline can synergistically inhibit glioblastoma cell viability with RCC2 silencing. In summary, our study demonstrated that RCC2 signaling is essential for GBM development. We provided evidence that RCC2 exerts a positive effect on G2-M progression. These findings may shed light on anti-RCC2 targeted therapy in GBM treatment. Funding: This work is supported by a General Research Fund grant (#14113519) from the University Grants Committee of Hong Kong. Citation Format: Tian Liu, Penelope Mei-Yu Or, Chi-Wai Wong, Wayne Lut-Heng Ho, Stanley Kwok-Kuen Cheung, Yubing Wang, Andrew M. Chan. RCC2 promotes glioblastoma through regulation of G2-M progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1971.